Spring seat and damper device

ABSTRACT

A damper device includes a first rotor, a second rotor, a plurality of elastic members, and a spring seat. The spring seat includes an end surface support portion and an outer periphery support portion. The end surface support portion includes a recess on a radially middle part thereof. The recess is recessed toward at least one of the elastic members. The end surface support portion supports one end surface of the at least one of the elastic members. The end surface support portion is supported by a pressing surface of a first accommodation portion of the first rotor and a pressing surface of a second accommodation portion of the second rotor. The outer periphery support portion supports part of a radially outer part of the at least one of the elastic members.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to Japanese Patent Application No.2020-030441, filed Feb. 26, 2020. The contents of that application areincorporated by reference herein in their entirety.

TECHNICAL FIELD

The present invention relates to a spring seat and a damper device.

BACKGROUND ART

A type of hybrid vehicle including an engine and an electric motor, forinstance, uses such a damper device having a torque limiter function asdescribed in Japan Laid-open Patent Application Publication No.2011-226572 in order to prevent transmission of an excessive torque froman output side to an engine side in engine start and so forth.

The damper device described in Japan Laid-open Patent ApplicationPublication No. 2011-226572 includes a damper part, composed of a sideplate provided as an input rotor, a hub plate provided as an outputrotor and a plurality of coil springs, and a torque limiter disposed onan outer peripheral side of the damper part. The damper part and thetorque limiter are coupled by rivets. Besides, a plate composing part ofthe torque limiter is fixed to a flywheel by bolts.

The plurality of coil springs of the damper part are herein disposed ina plurality of window portions of the side plate. When the side plateand the hub plate are rotated relative to each other, the coil springsare compressed between both plates in a rotational direction.Centrifugal forces herein act on the coil springs. Hence, whencompressed, the coil springs are moved radially outward. As a result,the coil springs slide against the window portions, whereby frictionresistance is generated between the coil springs and the side plate. Thedamper part degrades in performance of attenuating rotationalfluctuations due to the friction resistance.

In view of this, a pair of spring seats is attached to both ends of eachcoil spring. The pair of spring seats supports the end surfaces and partof a radially outer part of each coil spring, whereby the coil springsare prevented from sliding against the window portions.

In general, the damper device is herein provided with a stoppermechanism for restricting the angle of relative rotation (torsion angle)between the input rotor and the output rotor to a predetermined angularrange. The stopper mechanism is composed of, for instance, stop pinsmounted on the input rotor and circular-arc stopper holes provided inthe output rotor.

Enlarging the torsion angle between the input rotor and the output rotoras much as possible (i.e., widening of angle) is preferable for makingthe damper device obtain good performance of attenuating rotationalfluctuations. In order to achieve widening of angle, it is required toreliably elongate stopper holes in the output rotor.

However, when the spring seats are provided on both ends of therespective coil springs as described above, chances are often that thespring seats are disposed in positions radially overlapping with thestopper holes. Because of this, when the spring seats are provided, thestopper holes cannot be elongated; widening of angle is hindered.

BRIEF SUMMARY

It is an object of the present invention to enable a circumferentiallyelongated hole to be formed, as a component of a stopper mechanism, in adamper device in which a spring seat is installed.

(1) A spring seat according to the present invention is installed in adamper device including a first rotor, a second rotor and a plurality ofelastic members. The spring seat supports at least one end surface of atleast one of the plurality of elastic members. The first rotor includesa plurality of first accommodation portions. The plurality of firstaccommodation portions each include a pair of first pressing surfaces onboth circumferential end surfaces thereof. The second rotor is rotatablerelative to the first rotor. The second rotor includes a plurality ofsecond accommodation portions. The plurality of second accommodationportions each include a pair of second pressing surfaces on bothcircumferential end surfaces thereof. The plurality of elastic membersare accommodated in a plurality of pairs of the first and secondaccommodation portions. The plurality of elastic members elasticallycouple the first rotor and the second rotor in a rotational direction.

The spring seat includes an end surface support portion and an outerperiphery support portion. The end surface support portion includes arecess on a radially middle part thereof. The recess is recessed towardthe at least one of the plurality of elastic members. The end surfacesupport portion supports the at least one end surface of the at leastone of the plurality of elastic members. The end surface support portionis supported by one of the pair of first pressing surfaces of the firstaccommodation portion accommodating the at least one of the plurality ofelastic members and one of the pair of second pressing surfaces of thesecond accommodation portion accommodating the at least one of theplurality of elastic members. The outer periphery support portionsupports part of a radially outer part of the at least one of theplurality of elastic members.

The at least one of the elastic members is herein supported, through thespring seat, by one of the pair of first pressing surfaces of the firstaccommodation portion accommodating the at least one elastic member andone of the pair of second pressing surfaces of the second accommodationportion accommodating the at least one elastic member. The spring seatis provided with the recess on the end surface support portion thereof.Because of this, the protruding portion, configured to be fitted to therecess, can be formed on one of the pair of second pressing surfaces ofthe second accommodation portion. Therefore, when it is assumed to forma stopper mechanism for restricting relative rotation between the firstrotor and the second rotor by a stopper hole having a circular-arc shapeand a member penetrating the stopper hole, the stopper hole can beelongated at one end thereof toward the protruding portion formed on theabove-mentioned one of the pair of second pressing surfaces. As aresult, enlarging the torsion angle between the first rotor and thesecond rotor (i.e., widening of angle) is made possible.

(2) Preferably, the recess includes a hole circumferentially penetratingtherethrough. The recess, when thus provided with the hole, can beshaped as deeply as possible. As a result, the protruding portion on theabove-mentioned one of the pair of second pressing surfaces can beprotruded as largely as possible, whereby, for instance, theabove-mentioned stopper hole can be further elongated.

(3) Preferably, the first rotor includes a first plate and a secondplate that are disposed axially apart from each other at an interval. Inthis case, the second rotor is disposed axially between the first plateand the second plate.

(4) A damper device according to the present invention includes a firstrotor, a second rotor, a plurality of elastic members, a stoppermechanism, and the spring seat. The first rotor includes a plurality offirst accommodation portions. The plurality of first accommodationportions each include a pair of first pressing surfaces on bothcircumferential end surfaces thereof. The second rotor is rotatablerelative to the first rotor. The second rotor includes a plurality ofsecond accommodation portions. The plurality of second accommodationportions each include a pair of second pressing surfaces on bothcircumferential end surfaces thereof. The plurality of elastic membersare accommodated in a plurality of pairs of the first and secondaccommodation portions. The plurality of elastic members elasticallycouple the first rotor and the second rotor in a rotational direction.The stopper mechanism includes a stop member and a stopper hole. Thestop member is mounted on the first rotor. The stopper hole is providedin the second rotor. The stopper hole is circumferentially elongated andis penetrated by the stop member. The spring seat supports at least oneend surface of at least one of the plurality of elastic members and hasthe configuration specified as described above.

(5) Preferably, the second rotor includes a protruding portioncircumferentially protruding on at least one of the pair of secondpressing surfaces of the second accommodation portion accommodating theat least one of the plurality of elastic members. The protruding portionis fitted to the recess of the spring seat. In this case, the stopperhole extends at one circumferential end thereof toward the protrudingportion.

Overall, according to the present invention described above, acircumferentially elongated stopper hole can be formed, as a componentof a stopper mechanism, in a damper device in which a spring seat isinstalled; good performance of attenuating rotational fluctuations canbe obtained by the damper device.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of a torque limiter embedded damperdevice according to a preferred embodiment of the present invention.

FIG. 2 is a front view of a damper unit of the damper device shown inFIG. 1 .

FIG. 3 is a front view of a flange.

FIG. 4 is a side view of a spring seat.

FIG. 5 is a cross-sectional view of FIG. 4 taken along line V-V.

FIG. 6 is a chart showing torsional characteristics.

DETAILED DESCRIPTION

[Entire Configuration]

FIG. 1 is a cross-sectional view of a torque limiter embedded damperdevice 1 (hereinafter simply referred to as “damper device 1” on anas-needed basis) according to a preferred embodiment of the presentinvention. On the other hand, FIG. 2 is a front view of the damperdevice 1 in a condition that some constituent members are detachedtherefrom or are not illustrated in part. In FIG. 1 , line O-O indicatesa rotational axis. In FIG. 1 , an engine is disposed on the left side ofthe damper device 1, whereas a drive unit, including an electric motor,a transmission and so forth, is disposed on the right side of the damperdevice 1.

It should be noted that in the following explanation, the term “axialdirection” refers to an extending direction of the rotational axis O ofthe damper device 1. On the other hand, the term “circumferentialdirection” refers to a circumferential direction of an imaginary circleabout the rotational axis O, whereas the term “radial direction” refersto a radial direction of the imaginary circle about the rotational axisO. It should be noted that the circumferential direction is not requiredto be perfectly matched with that of the imaginary circle about therotational axis O, and is conceptualized as encompassing, for instance,a right-and-left direction defined based on a window portion and awindow hole, both of which are illustrated in an upper part of FIG. 2 .Likewise, the radial direction is not required to be perfectly matchedwith a diameter direction of the imaginary circle about the rotationalaxis O, and is conceptualized as encompassing, for instance, anup-and-down direction defined based on the window portion and the windowhole, both of which are illustrated in the upper part of FIG. 2 .

The damper device 1 is a device provided between a flywheel and an inputshaft of the drive unit (both of which are not illustrated in thedrawings) in order to limit a torque transmitted between the engine andthe drive unit and attenuate rotational fluctuations. The damper device1 includes a torque limiter unit 10 and a damper unit 20.

[Torque Limiter Unit 10]

The torque limiter unit 10 is disposed on the outer peripheral side ofthe damper unit 20. The torque limiter unit 10 limits a torquetransmitted between the flywheel and the damper unit 20. The torquelimiter unit 10 includes first and second side plates 11 and 12, afriction disc 13, a pressure plate 14 and a cone spring 15.

The first and second side plates 11 and 12 are fixed to each other by aplurality of rivets. The friction disc 13 includes a core plate 131 anda pair of friction members 132. The pressure plate 14 and the conespring 15 are disposed between the first side plate 11 and the frictiondisc 13. The cone spring 15 presses the friction disc 13 onto the secondside plate 12 through the pressure plate 14.

[Damper Unit 20]

The damper unit 20 is composed of an input-side plate 21 (exemplaryfirst rotor), a hub flange 22 (exemplary second rotor) and a damper part23 disposed between the input-side plate 21 and the hub flange 22.

<Input-Side Plate 21>

The input-side plate 21 includes a first plate 211 and a second plate212 (both of which will be hereinafter collectively referred to as “theinput-side plate 21” on an as-needed basis). Each of the first andsecond plates 211 and 212 is an annular member having a center hole. Thefirst and second plates 211 and 212 are fixed to each other at apredetermined axial interval by four stop pins 24. Therefore, the firstand second plates 211 and 212 are immovable relative to each other inboth axial and rotational directions. Besides, the core plate 131 of thefriction disc 13 is fixed at the inner peripheral part thereof to thefirst plate 211 by the stop pins 24.

Each of the first and second plates 211 and 212 is provided with a pairof first window portions 21 a (exemplary first accommodation portions)and a pair of second window portions 21 b. The pair of first windowportions 21 a is disposed in opposition to each other through therotational axis O. FIG. 2 depicts the pair of first window portions 21 aand one of the pair of second window portions 21 b in the second plate212, but the configurations of the window portions 21 a and 21 b aresimilarly true of those in the first plate 211. The pair of first windowportions 21 a is formed by cutting and raising each plate 211, 212. Eachfirst window portion 21 a includes a pair of pressing surfaces 21 c(exemplary first pressing surfaces) on both circumferential end surfacesthereof and includes a pair of support portions on the outer and innerperipheral edges thereof. Besides, the pair of second window portions 21b is disposed in opposition to each other through the rotational axis O,while shifting at an angular interval of 90 degrees from the pair offirst window portions 21 a. The pair of second window portions 21 b is apair of rectangular openings axially penetrating each plate 211, 212,and each includes a pair of pressing surfaces 21 d on bothcircumferential end surfaces thereof

<Hub Flange 22>

The hub flange 22 is a member for transmitting a torque, inputtedthereto from the input-side plate 21, to an output-side device. The hubflange 22 includes a hub 221 and a flange 222. As shown in FIG. 2 , thehub 221 and the flange 222 are integrated by a plurality of teeth and aplurality of recesses with which the plural teeth are meshed.

The hub 221 is a tubular member and is disposed within the center holesof the first and second plates 211 and 212. The hub 221 is provided witha spline hole in the inner peripheral part thereof, whereby anoutput-side member is capable of being spline-coupled to the splinehole.

As shown in FIGS. 2 and 3 , the flange 222 is made in the shape of adisc and is disposed axially between the first plate 211 and the secondplate 212. The flange 222 includes a center hole, a pair of first windowholes 22 a (exemplary second accommodation portions), a pair of secondwindow holes 22 b, and four stopper holes 22 c.

The pair of first window holes 22 a is disposed in opposition to eachother through the rotational axis O while being provided incorresponding positions to the pair of first window portions 21 a of thefirst plate 211 and that of the second plate 212. Each first window hole22 a includes a pair of pressing surfaces 22 d (exemplary first pressingsurfaces) on both circumferential end surfaces thereof. Besides, each ofthe pair of pressing surfaces 22 d includes a protruding portion 22 e,protruding to bulge toward the other opposed pressing surface 22 d, on aradially center part thereof.

The pair of second window holes 22 b is disposed in opposition to eachother through the rotational axis O, while shifting at an angularinterval of 90 degrees from the pair of first window holes 22 a. Inother words, the pair of second window holes 22 b is provided incorresponding positions to the pair of second window portions 21 b ofthe first plate 211 and that of the second plate 212. Each second windowhole 22 b is made in the shape of a circular arc, and a pitch radius (aradius at the middle position of the radial width) of each second windowhole 22 b is defined radially inside the radially center position ineach first window hole 22 a. Each second window hole 22 b includes apair of pressing surfaces 22 f on both circumferential end surfacesthereof, the distance between the pair of pressing surfaces 22 f is setto be longer than that between the pair of pressing surfaces 21 d ofeach second window portion 21 b in the input-side plate 21.

The stopper holes 22 c are elongated holes, each of which extends in theshape of a circular arc. The stopper holes 22 c are provided on bothsides of the respective first window holes 22 a in the circumferentialdirection. Each stopper hole 22 c extends, at one end thereof locatedapart from the first window hole 22 a adjacent thereto, to a positionradially outside the second window hole 22 b near thereto. On the otherhand, each stopper hole 22 c extends, at the other end thereof locatedcloser to the adjacent first window hole 22 a, toward adjacent one ofthe pair of protruding portions 22 e in the adjacent first window hole22 a. Specifically, each stopper hole 22 c reaches a line segment L atthe other end thereof located closer to the adjacent first window hole22 a. The line segment L is herein defined as an imaginary line segmentconnecting the outer and inner peripheral parts (not provided with theprotruding portions 22 e) of each end surface of each first window hole22 a.

In the configuration described above, each stopper hole 22 c can beshaped to extend longer at the end thereof located closer to theadjacent first window hole 22 a than in a configuration that theadjacent first window hole 22 a is not provided with the pair ofprotruding portions 22 e. As a result, the angle formed by therotational axis O and each pair of stop pins 24 interposing therebetweeneach first window hole 22 a can be set to approach 90 degrees. It shouldbe noted that the pitch radii of the four stopper holes 22 c are equal.In other words, the four stopper holes 22 c are aligned on thecircumference of an imaginary identical circle.

Besides, the stopper holes 22 c are axially penetrated by the stop pins24, respectively. Because of this, the input-side plate 21 and the hubflange 22 are rotatable relative to each other within a range that eachstop pin 24 is movable within each stopper hole 22 c. In other words,the stop pins 24 and the stopper holes 22 c compose a stopper mechanism25. The input-side plate 21 and the hub flange 22 are prevented fromrotating relative to each other when each stop pin 24 makes contact withone end surface of each stopper hole 22 c.

<Damper Part 23>

The damper part 23 is a mechanism for elastically coupling theinput-side plate 21 and the hub flange 22 in the rotational direction.As shown in FIGS. 1 and 2 , the damper part 23 includes two coil springs27, two resin members 28, two pairs of spring seats 30, each pair ofwhich supports both end surfaces of each coil spring 27, and ahysteresis generating mechanism 31 (see FIG. 1 ).

The coil springs 27 are accommodated in the pair of first window holes22 a of the flange 222, respectively, whereas the resin members 28 areaccommodated in the pair of second window holes 22 b of the flange 222,respectively. Besides, the coil springs 27 are axially and radiallysupported by the pair of first window portions 21 a of the first plates211 and that of the second plates 212, respectively, whereas the resinmembers 28 are axially and radially supported by the pair of secondwindow portions 21 b of the first plate 211 and that of the second plate212.

It should be noted that each resin member 28 is disposed in each secondwindow portion 21 b of the input-side plate 21 without anycircumferential gap. On the other hand, each resin member 28 is shorterthan the circumferential width of each second window hole 22 b of theflange 222. In other words, in a neutral state without relative rotationbetween the input-side plate 21 and the hub flange 22 (i.e., the torsionangle is “0”), gaps (to be described below in detail) are producedbetween both ends of each resin member 28 and the pair of pressingsurfaces 22 f of each second window hole 22 b of the flange 222.

Each pair of spring seats 30 is disposed on both circumferential ends ofeach first window hole 22 a of the flange 222. Each pair of spring seats30 supports the end surfaces of each coil spring 27 and supports part ofthe outer peripheral part (both circumferential ends) of each coilspring 27.

As shown in FIGS. 4 and 5 , each spring seat 30 includes an end surfacesupport portion 301 and an outer periphery support portion 302. Itshould be noted that FIG. 4 is a side view of each spring seat 30 (asseen from one side in the circumferential direction), whereas FIG. 5 isa cross-sectional view of FIG. 4 taken along line V-V.

The end surface support portion 301 supports the one-side end surface ofeach coil spring 27, while being supported by the one-side pressingsurface 21 c of each first window portion 21 a accommodating each coilspring 27 in each plate 211, 212 composing the input-side plate 21 andthe one-side pressing surface 22 d of each first window hole 22 aaccommodating each coil spring 27 in the flange 222. As shown in FIG. 5, the end surface support portion 301 is provided with a recess 301 a,recessed in a circular-arc shape toward each coil spring 27, on thesurface thereof supported by the one-side pressing surface 22 d of eachfirst window hole 22 a accommodating each coil spring 27. Besides, therecess 301 a includes a hole 301 b circumferentially penetrating amiddle part thereof (i.e., a part located in the middle thereof in bothradial and axial directions). Furthermore, the one-side protrudingportion 22 e of each first window hole 22 a accommodating each coilspring 27 in the flange 222 is fitted into the recess 301 a.

As described above, each coil spring 27 is accommodated in each firstwindow portion 21 a of the first plate 211, that of the second plate212, and each first window hole 22 a of the flange 222 through each pairof spring seats 30 without any circumferential gap.

The outer periphery support portion 302 is provided to extend from theouter peripheral end of the end surface support portion 301 in thecircumferential direction. The outer periphery support portion 302 isdisposed between the outer peripheral part of one end of each coilspring 27 and both the inner peripheral surface of each first windowhole 22 a and the inner peripheral surface of each first window portion21 a of each plate 211, 212. Because of this, even when each coil spring27 is moved to the outer peripheral side either by a centrifugal forceor in a compressed state, contact can be avoided between each coilspring 27 and both each first window hole 22 a and each first windowportion 21 a of each plate 211, 212.

The hysteresis generating mechanism 31 is disposed axially between thehub flange 22 and the first and second plates 211 and 212. As shown inFIG. 1 , the hysteresis generating mechanism 31 includes a first bushing41, a second bushing 42, a third bushing 43 and a cone spring 44.

The first and second bushings 41 and 42 are disposed on the outerperipheral surface of the hub 221, while being disposed axially betweenthe flange 222 and the inner peripheral end of the first plate 211. Thesecond bushing 42 is engaged with the hub 221, while being non-rotatablerelative thereto. The second bushing 42 makes contact by friction withthe first bushing 41. The third bushing 43 is disposed axially betweenthe flange 222 and the inner peripheral end of the second plate 212. Thethird bushing 43 is engaged with the second plate 212, while beingnon-rotatable relative thereto. The third bushing 43 makes contact byfriction with the flange 222. The cone spring 44 is disposed in acompressed state between the third bushing 43 and the second plate 212.

Due to the configuration described above, when the hub flange 22 and thefirst and second plates 211 and 212 are rotated relative to each other,a hysteresis torque is generated.

[Action]

A torque, transmitted from the engine to the flywheel, is inputted tothe damper unit 20 through the torque limiter unit 10. In the damperunit 20, the torque is inputted to the input-side plate 21 to which thefriction disc 13 of the torque limiter unit 10 is fixed, and is thentransmitted to the hub flange 22 through the coil springs 27 and theresin members 28. Subsequently, power is transmitted from the hub flange22 to the electric motor, the transmission, a power generator and soforth disposed on the output side.

Incidentally, for instance in starting the engine, chances are that anexcessive torque is transmitted from the output side to the enginebecause the amount of inertia is large on the output side. In such acase, the magnitude of torque to be transmitted to the engine side islimited to a predetermined value or less by the torque limiter unit 10.

<Positive-Side Torsional Characteristics>

Explanation will be given for positive-side torsional characteristicsobtained in the damper unit 20, namely, characteristics obtained when atorque is inputted from the engine (i.e., in input of a positive-sidetorque).

When the positive-side torque is inputted, the input-side plate 21 isrotated in an R1 direction in FIG. 2 . Because of this, each of the twocoil springs 27 is compressed between the spring seat 30 supported bythe R2-side pressing surface 21 c of each first window portion 21 a ineach plate 211, 212 composing the input-side plate 21 and the springseat 30 supported by the R1-side pressing surface 22 d of each firstwindow hole 22 a in the flange 222.

It should be noted that as shown in FIG. 2 , although each resin member28 is supported by each second window portion 21 b of each plate 211,212 composing the input-side plate 21 without any gap in the neutralstate, circumferential gaps, each corresponding to a torsion angle θ1,are produced on the R1 and R2 sides of each resin member 28 in eachsecond window hole 22 b of the flange 222. On the other hand,circumferential gaps, each corresponding to a torsion angle θ2, areproduced on the R1 and R2 sides of each stop pin 24 in each stopper hole22 c. Here, the circumferential gaps (hereinafter simply referred to as“gaps”) are set to establish the following relation.

θ1<θ2

Due to the gap settings described above, each resin member 28 is notcompressed until the torsion angle between the input-side plate 21 andthe hub flange 22 reaches θ1 (it should be noted that the term “torsionangle” hereinafter refers to the torsion angle between the input-sideplate 21 and the hub flange 22). When the torsion angle exceeds θ1, eachresin member 28 is compressed between the R2-side pressing surfaces 21 dof each second window portion 21 b in each plate 211, 212 composing theinput-side plate 21 and the R1-side pressing surface 22 f of each secondwindow hole 22 b in the flange 222. Because of this, the positive-sidetorsional characteristics are obtained as shown in FIG. 6 ;characteristic C1 is obtained until the torsion angle reaches θ1,whereas characteristic C2 is obtained after the torsion angle reachesθ1.

Then, when the torsion angle reaches θ2, each stop pin 24 makes contactwith the R1-side end surface of each stopper hole 22 c, whereby theinput-side plate 21 and the hub flange 22 are prevented from rotatingrelative to each other.

<Negative-Side Torsional Characteristics>

Explanation will be given for negative-side torsional characteristicsobtained in the damper unit 20, namely, characteristics obtained when atorque is inputted reversely from the drive unit (i.e., in input of anegative-side torque).

When the negative-side torque is inputted, the hub flange 22 is rotatedin the R1 direction with respect to the input-side plate 21 in FIG. 2 .Because of this, each of the two coil springs 27 is compressed betweenthe spring seat 30 attached to the R2-side pressing surface 22 d of eachfirst window hole 22 a in the hub flange 22 and the spring seat 30attached to the R1-side pressing surface 21 c of each first windowportion 21 a in each plate 211, 212 composing the input-side plate 21.

Each resin member 28 is actuated in a similar manner to when thepositive-side torque is inputted. Specifically, each resin member 28 isnot compressed until the torsion angle reaches −θ1; when or before thetorsion angle reaches −θ1, low-stiffness torsional characteristic C1 isobtained as shown in FIG. 6 . Then, when the torsion angle exceeds −θ1,compression of each resin member 28 begins between the R2-side pressingsurface 22 f of each second window hole 22 b in the hub flange 22 andthe R1-side pressing surface 21 d of each second window portion 21 b ineach plate 211, 212 composing the input-side plate 21. Because of this,when the torsion angle exceeds −θ1, high-stiffness torsionalcharacteristic C2 is obtained as shown in FIG. 6 .

When the torsion angle reaches −θ2, each stop pin 24 makes contact withthe R2-side end surface of each stopper hole 22 c, whereby theinput-side plate 21 and the hub flange 22 are prevented from rotatingrelative to each other.

In the preferred embodiment described above, each spring seat 30 isprovided with the recess 301 a, and one of the protruding portions 22 eprovided in each first window hole 22 a of the flange 222 is fitted intothe recess 301 a. Besides, the stopper hole 22 c, located adjacent toeach first window hole 22 a, extends at one end thereof toward theabove-mentioned one of the protruding portions 22 e. Because of this,the stopper hole 22 c can be elongated in the circumferential direction.In other words, enlarging the torsion angle between the input-side plate21 and the hub flange 22 (i.e., widening of angle) is made possible,compared to a configuration that each spring seat 30 is not providedwith the recess 301 a, whereas each first window hole 22 a includes endsurfaces, each of which is made in the shape of a flat surface (withoutthe protruding portion 22 e).

Besides, due to a similar reason to the above, adjacent ends of thestopper holes 22 c provided on both sides of each first window hole 22 ain the flange 222 can be made closer to each other. As a result, theangle formed by the rotational axis O and the stop pins 24 disposed onboth sides of each first window hole 22 a can be set to approach 90degrees, whereby inhomogeneity in strength of the input-side plate 21and the hub flange 22 can be inhibited.

[Other Preferred Embodiments]

The present invention is not limited to the preferred embodimentdescribed above, and a variety of changes or modifications can be madewithout departing from the scope of the present invention.

(a) In the preferred embodiment described above, the hub flange 22 iscomposed of two members: the hub 221 and the flange 222. However, thehub flange 22 may be composed of a single member.

(b) In the preferred embodiment described above, each coil spring isprovided with the spring seats on both ends thereof, respectively.Alternatively, each coil spring may be provided with the spring seatonly one end thereof. Yet alternatively, each coil spring may beprovided with the spring seat according to the present invention on oneend thereof, while being provided with another spring seat of aheretofore known type on the other end thereof.

(c) Components provided as the elastic members are not limited to twocoil springs and two resin members. For example, all the componentsprovided as the elastic members may be coil springs, and the number ofthe elastic members is not limited to a specific number.

(d) In the preferred embodiment described above, the present inventionis applied to the torque limiter embedded damper device but is similarlyapplicable to another type of damper device.

(e) Torsional characteristics are not limited to those shown in FIG. 6 .

REFERENCE SIGNS LIST

-   21 Input-side plate (first rotor)-   211 First plate-   212 Second plate-   21 a First window portion (first accommodation portion)-   21 c Pressing surface (first pressing surface)-   22 c Hub flange (second rotor)-   22 a First window hole (second accommodation portion)-   22 c Stopper hole-   22 d Pressing surface (second pressing surface)-   22 e Protruding portion-   24 Stop pin-   25 Stopper mechanism-   27 Coil Spring (elastic member)-   28 Resin member (elastic member)-   30 Spring seat-   301 End surface support portion-   301 a Recess-   301 b Hole-   302 Outer periphery support portion

What is claimed is:
 1. A damper device comprising: a first rotorincluding a plurality of first accommodation portions, the plurality offirst accommodation portions each including a pair of first pressingsurfaces on both circumferential end surfaces thereof; a second rotorrotatable relative to the first rotor, the second rotor including aplurality of second accommodation portions and a protruding portion, theplurality of second accommodation portions each including a pair ofsecond pressing surfaces on both circumferential end surfaces thereof,the protruding portion circumferentially protruding on at least one ofthe pair of second pressing surfaces of the second accommodationportion; a plurality of elastic members accommodated in a plurality ofpairs of the first and second accommodation portions, the plurality ofelastic members configured to elastically couple the first rotor and thesecond rotor in a rotational direction; and a spring seat configured tosupport at least one end surface of at least one of the plurality ofelastic members, the spring seat including an end surface supportportion including a recess on a radially middle part thereof, the recessrecessed toward the at least one of the plurality of elastic members,the end surface support portion configured to support the at least oneend surface of the at least one of the plurality of elastic members, theend surface support portion supported by one of the pair of firstpressing surfaces of the first accommodation portion accommodating theat least one of the plurality of elastic members and one of the pair ofsecond pressing surfaces of the second accommodation portionaccommodating the at least one of the plurality of elastic members, andan outer periphery support portion configured to support part of aradially outer part of the at least one of the plurality of elasticmembers, wherein the protruding portion of the second rotor is fitted tothe recess of the spring seat.
 2. The damper device according to claim1, wherein the recess includes a hole circumferentially penetratingtherethrough.
 3. The damper device according to claim 1, wherein thefirst rotor includes a first plate and a second plate, the first andsecond plates disposed axially apart from each other at an interval, andthe second rotor is disposed axially between the first plate and thesecond plate.
 4. The damper device according to claim 1, furthercomprising a stopper mechanism including a stop member and a stopperhole, the stop member mounted on the first rotor, the stopper holeprovided in the second rotor, the stopper hole circumferentiallyelongated, the stopper hole penetrated by the stop member.
 5. The damperdevice according to claim 4, wherein the stopper hole extends at onecircumferential end thereof toward the protruding portion.